Sampling Of Common Communicable Diseases

Quality Management Systems Pre-Analytic: Sampling of Communicable Diseases

Key to obtaining Successful Samples for Analytic Stage  Right sample collection  Right time to collect sample for disease  Right methodology for the transportation

of sample  Right Lab to be chosen

Role Physician Identify right pt Order relevant tests Collected appropriate specimens of good quality

Label appropriately and fill Proforma

Role Physician Transport properly to Lab Record properly to Lab LAB ( Analytic Stage)

Role of LAB Perform accurate and precise analysis Document and report Interpret Take timely action on right pt (Post Analytic)

Influenza 

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Kit Storage and Stability – store at 15-30 C out of direct sunlight. Kit contents are stable until the expiration date on the outer box. Don’t freeze. SAMPLE COLLECTION AND STORAGE –  NASAL SWAB SAMPLE  SAMPLE TRANSPORT and STORAGE • Samples should be tested a.s.a.p. after collection. • Do not use any kind of transport media store or transfer the samples. • Samples maybe stored refrigerated ( 2-8 C) in a clean, dry, closed container for up to one hour. • Swab Specimens can also be stored at room temp. for up to 48hrs.

Dengue  Sample collection and storage

Serum and plasma  Specimens maybe stored at 2-8 C for up to 3 days before testing  For long term storage, specimen kept below -20 C  When using Lateral Flow Dengue IgM/IgG Test Card, store cards at 2-30 C. Store the conjugate reagent at 2-8 C. Don’t freeze or use beyond the expiration date. 

HIV  Sample collection 

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Serum and Plasma – specimen of choice for a majority of the Rapid testing Devices Some of the assays have been adapted to allow the use of Whole Blood, Saliva, Oral Fluids and Urine. Oral Fluids and Urine Specimens are stable for extended periods at room temp. and can be mailed or shipped without degradation

Measles 

Sample collection and storage 

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Attempt to obtain sample a.s.a.p after onset of rash ( virus is recovered within the 1st 3 days) but up to 7 days is acceptable. Nasal/Throat swabs ( nasopharyngeal aspirate) Urine specimen – centrifuge soon after collection, store at 4 C transport to lab on wet ice. Should send to lab within 48hrs so it can be processed and frozen at -70 C for optimal virus recovery Blood Samples/serum – virus can be isolated from lymphocytes

Rubella  Sample collection and storage 

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Serum ( if no serum separation facilities are available whole blood is to be sent to Lab within 24hrs) Dried blood spots Oral Fluids – gently rub a small sponge on a stick along the gum and dentine interface for about 1min.

Typhoid  Sample collection and storage 

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5-10ml of blood collected by venepuncture inoculated into 50-100ml bile broth (0.5%) Bone Marrow, Stool specimen ( culture) Bacterium occurs early in the disease, cultures are positive in; • 1wk – 90 % , 2wk – 75%, 3wk – 60%, 4wk – 25% • Serum agglutinins increase abruptly in 2-3wks, so Widal Test would be useful then

Cholera 

Sample collection  

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Stool or Rectal swabs Transported to Lab in transport medium ( cary-blair medium, VR medium, Alkaline Peptone) If not transport medium --- cotton tipped rectal swab soaked in the liquid stool should be placed in a sterile plastic bag and tightly sealed Specimens should be collected before pt recieves antibiotics

Leptospirosis  Sample collection

Blood ( ~ 5ml ), serum ( freeze at -20 C to -80C if not used within 5 days)  CSF  Urine – may contain leptospires for wks to mths. 

• Urine culture should be plated within 2hrs or less to ensure viability of leptospires 

Affected organs